Systems, devices, methods for delivering hydrogel compositions with self-purging to prevent clogging

ABSTRACT

A hydrogel composition is formed by conveying separate first and second liquid components subject to a selectively applied application pressure P(A) into an outlet path for mixing and discharge. A liquid flushing agent is automatically conveyed into the outlet path subject to a substantially constantly applied purge pressure P(P) when the application of P(A) is interrupted, to continuously flush residual hydrogel composition from the outlet path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit to and priority of U.S. ProvisionalPatent Application No. 61/320,909 filed on Apr. 5, 2010 entitled“Systems, Devices, Methods For Delivering Hydrogel Compositions WithSelf-Purging To Prevent Clogging,” the entire contents of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to systems, devices, and methods forapplying compositions of materials that polymerize or cross-link at theinstance of use, and, in particular, that apply compositions of thistype in the medical field.

BACKGROUND OF THE INVENTION

Systems, devices, and methods for applying compositions of materialsthat polymerize or cross-link at the instance of use typically consistof an applicator that brings together two liquid components (e.g.,albumin and PEG) into a spray tip. Within the spray tip, the liquidcomponents mix and begin a rapid polymerization process to form ahydrogel. As long as the operator maintains the continuous flow of thetwo components into and through the spray tip, the spray tip will notclog up. However, as soon as the operator stops the flow of thecomponents, a residual amount of the components remains within the spraytip and continues to polymerize into a solid hydrogel, and thus clog thespray tip.

Conventional spray tip devices include a port for pressurized air to bedirected through the spray tip, to prevent the hydrogel from cloggingwithin the spray tip. However, this device is cumbersome and requiresaccessories such as tubing, a pressure regulator, and a pressurized airsource.

SUMMARY OF THE INVENTION

The invention provides systems, devices, and methods that systematicallyremove undischarged, residual mixtures of first and second liquidcomponents from an outlet path of an applicator.

One aspect of the invention provides self-purging systems and methodsfor delivering a hydrogel material formed by mixing first and secondliquid components. The systems and methods comprise an applicator sizedand configured to mix the first and second liquid components and formthe hydrogel composition. The applicator includes separate inlet pathsthat separately convey the first and second liquid components subject toa selectively applied application pressure P(A) into a single outletpath for mixing and formation of the hydrogel composition for dischargefrom the single outlet path.

The systems and methods also include a purge assembly comprising asource of liquid flushing agent subject to a substantially constantlyapplied purge pressure P(P), which is maintained at a magnitude that isless than P(A). The purge assembly further includes a purging pathcoupling the source to the single outlet path of the applicator toconvey liquid flushing agent into single the outlet path subject to thesubstantially constantly applied purge pressure P(P).

The purge assembly includes a valve assembly communicating with thepurging path and the single outlet path. The valve assembly is operablein response to localized pressure conditions between first and secondflow conditions.

The first flow condition permits the flow and mixing of the first andsecond liquid components but not the liquid flushing agent in the singleoutlet path subject to the application of P(A), for dispensing thehydrogel composition from the single outlet path.

The second flow condition permits the flow of liquid flushing agent butnot the first and second liquid components in the single outlet pathsubject to the substantially constantly applied purge pressure P(P), tocontinuously flush residual hydrogel composition from the single outletpath.

The valve assembly is automatically placed in the first flow conditionin response to localized pressure conditions whenever P(A) is appliedand is automatically placed in the second flow condition in response tolocalized pressure conditions during an interruption of the applicationof P(A).

Features and advantages of the inventions are set forth in the followingDescription and Drawings, as well as in the appended Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a system delivering a hydrogelcomposition with a self-purging assembly.

FIG. 2 is an assembled perspective view of the system shown in FIG. 1.

FIG. 3 is a perspective view of the system shown in FIG. 2 in use, withthe purge assembly in a first flow condition permitting the flow andmixing of the first and second liquid components within an applicator toform and dispense the hydrogel composition, but not permitting the flowof a liquid flushing agent into the applicator.

FIG. 4 is a perspective view of the system shown in FIG. 2 in use, withthe purge assembly in a second flow condition permitting the flow ofliquid flushing agent subject to a substantially constantly appliedpurge pressure to continuously flush residual hydrogel composition fromthe applicator.

DESCRIPTION OF PREFERRED EMBODIMENTS

This detailed description is meant to be illustrative only and is notmeant to limit the invention. For example, a dual barrel syringe systemis disclosed. Three barrel systems, or other systems and arrangementsmay also be used.

FIGS. 1 and 2 show a system 10 for delivering a material that is formedfrom two or more liquid components 12 and 14, which are mixed at theinstance of use. When mixed, the liquid components begin a rapidpolymerization process to form a hydrogel composition 16, as FIG. 3shows.

The components 12 and 14 can vary. For example, the first component 12can comprise a liquid material having one or more nucleophilic (electrondonator) groups. The second component 14 can comprise a liquid materialhaving one or more electrophilic (electrode withdrawing) groups. As FIG.3 shows, the formative components 12 and 14, upon mixing, cross-link,transforming from a liquid state to a biocompatible hydrogel composition16 (in a process called “gelation”).

After gelation, the hydrogel composition 16 exhibits desired mechanicalproperties that can include adhesive strength, cohesive strength, andelasticity. In a representative embodiment, the hydrogel composition 16is intended for use in the medical field. In this arrangement, dependingupon its mechanical properties, the hydrogel composition 16 can be used,e.g., as a tissue sealant, a tissue adhesion barrier, a tissue voidfiller, or a carrier for a therapeutic agent.

In one representative example, the nucleophilic first component 12 cancomprise a protein solution (e.g., albumin) and the second electrophiliccomponent 14 can comprise a polymer (e.g., poly(ethylene glycol) orPEG).

The delivery system 10 includes a dual syringe assembly 18. The dualsyringe assembly 18 can be conventional in construction and is shown inFIGS. 1 and 2 for illustration purposes only. The dual syringe assembly18 includes a pair of side-by-side syringe barrels 20 and 22. One barrel20 is sized and configured to receive the first liquid component 12, andthe other barrel 22 is sized and configured to receive the second liquidcomponent 14. A syringe piston 24 and 26 is advanceable within eachsyringe barrel 20 and 22, respectively, to dispense the respectivecomponent 12 and 14 from the dispensing end of the respective barrel 20and 22.

The syringe pistons 24 and 26 are joined by a clip 28. The syringe clip28 mechanically links the syringe pistons 24 and 26 together for commonadvancement inside their respective syringe barrels 20 and 22. Theoperator is thereby able to hold and operate dual syringe barrels 20 and22 in the same way as a single syringe barrel.

The system 10 includes an applicator 30. The applicator 30 includes atone end a pair of luer-type fittings 32 that couple to the dispensingends of the syringe barrels 20 and 22.

The applicator 30 includes interior channels 34 and 36 coupled to theluer fittings 32. The channels 34 and 36 merge at a Y-junction 38 into asingle outlet path 40. The applicator 30 maintains two liquid components12 and 14 dispensed by the dual syringe barrels 20 and 22 separate untilthey reach the Y-junction 38. The clip 28 ensures even application ofindividual components 12 and 14 through the applicator at a givenapplication pressure P(A).

At the Y-junction 38 and then through the outlet path 40, the twocomponents 12 and 14 mix and cross-link while flowing subject to theapplication pressure P(A) in the liquid state, in a process that will,in shorthand, be called “channel-mixing.” During channel mixing,gelation begins to form the hydrogel composition 16 as it is dispensedfrom outlet path 40. The outlet path 40 can be sized and configured,e.g., to serve as a spray tip for discharging the gelating hydrogelcomposition as a spray into contact with tissue.

The parts of the dual syringe assembly 18 and applicator 30 can be made,e.g., by molding medical grade plastic materials, such as polycarbonateand acrylic.

Termination of the application pressure P(A) by operation of the dualsyringe assembly 18 can leave undischarged, residual mixtures of thefirst and second components 12 and 14 within the outlet path 40. Theresidual mixtures can undergo further gelation within the outlet path 40to form the hydrogel composition 16. Presence of the hydrogelcomposition 16 within the outlet path 40 can clog or impede thesubsequent passage of liquids through the outlet path 40.

To systematically remove undischarged, residual mixtures of the firstand second components 12 and 14 from the outlet path 40, the system 10includes a purging assembly 42 coupled to the applicator 30. The purgingassembly 42 includes a source 44 of a liquid flushing agent 46, e.g.,water, and when used in the medical field, sterile water. The purgingassembly 42 also includes a purging path 48 that leads from the source44 to the outlet path 40 of the applicator 30. The purging path 48communicates with the outlet path 30.

The source 44 is subject to an applied preselected purging pressureP(P). The purging pressure P(P) is continuously applied and is selectedto be less than the application pressure P(A), for reasons that will bedescribed later.

The purging pressure P(P) normally urges the liquid flushing agent 46from the source 44 through the purging path 48 toward the outlet path40.

Within the outlet path 40, the liquid flushing agent 46 dischargesresidual mixtures of the first and second components 12 and 14 from theoutlet path 40 at the purging pressure P(P), before gelation of thehydrogel composition substantially occurs. Clogging of the outlet path40 is thereby prevented or moderated.

The purging assembly includes a first valve V1 in the purging path 48between the source 44 and the outlet path 40 of the applicator 30. Thevalve V1 operates in response to localized pressure conditions withinthe purging path 48 between a closed condition and an opened condition.In the closed condition, the valve V1 prevents the pressurized flow ofthe liquid flushing agent 46 through the purging path 48. In the openedcondition, the valve V1 allows the pressured flow of the liquid flushingagent 46 through the purging path 48. The valve V1 is sized andconfigured to assume the closed condition when pressure conditions inthe purging path 48 downstream of the valve V1 (i.e., toward the outletpath 40) exceed the pressure conditions in the purging path 48 upstreamof the valve V1 (i.e., toward the source 44).

The applicator 30 includes a second valve V2 in the channel 34 and athird valve V3 in the channel 36 in an upstream flow direction from theY-junction 38. Each valve V2 and V3 operates in response to localizedpressure conditions within the respective channels 34 and 36 between aclosed condition and an opened condition. In the closed condition, eachvalve V2 and V3 prevents the back flow of liquid through the respectivechannel 34 and 36 from the Y-junction 38 toward the syringe assembly 18.In the opened condition, each valve V2 and V3 allows the flow of liquidthrough the respective channel 34 and 36 toward the Y-junction 38. Eachvalve V2 and V3 is sized and configured to assume the closed conditionwhen pressure conditions upstream of the valve V2 and V3 in therespective channel 34 and 36 (i.e., toward the syringe assembly 18) areless than the pressure conditions in the channels 34 and 36 downstreamof the valves V2 and V3 (i.e., toward the Y-junction 38 and outlet 40).

By selecting the purging pressure P(P) to be less than the applicationpressure P(A) (as above described), the valve V1 will occupy the closedcondition and the valves V2 and V3 will occupy the opened conditionwhenever the dual syringe assembly 18 is operated to apply theapplication pressure P(A), as FIG. 3 shows, comprising a first flowcondition. In the first flow condition, during the application of thepressure P(A), the two liquid components 12 and 14 enter the channels 34and 36 of the applicator 30, flow through the open valves V2 and V3 toconverge at the Y-junction 38, and proceed through the outlet path 40,undergoing channel-mixing. In the first flow condition, during theapplication of the pressure P(A), the forming hydrogel composition 16 isdispensed from the outlet path 40. In the first flow condition, thevalve V1 is in the closed condition—because P(A) exceeds P(P)—and theliquid flushing agent 46 is prevented from flowing from the source 44into the outlet path 40.

When the application pressure P(A) is removed, e.g., when the operatorseeks to interrupt the discharge of the forming hydrogel composition 16from outlet path 40, the pressure conditions at the valves V1, V2, andV3 change, as FIG. 4 shows, comprising a second flow condition. In thesecond flow condition, the pressure condition upstream of the valve V1(i.e., the constantly applied preselected purging pressure P(P)) exceedsthe pressure conditions downstream of the valve V1 (because theapplication pressure P(A) is no longer being applied).

As FIG. 4 shows, the valve V1 assumes the opened condition, and thevalves V2 and V3 assume the closed condition, to thereby allow thepressured flow of the liquid flushing agent 46 (in some embodiments, agas flushing agent can be employed) through the purging path 48 and intoand through the outlet path 40. The liquid flushing agent 46 dischargesresidual mixtures of the first and second components 12 and 14 from theoutlet path 40 at the purging pressure P(P).

Because the purging pressure P(P) is constantly applied, the flow of theliquid flushing agent into the outlet path 40 occurs substantiallysimultaneously with the cessation of the application pressure P(A).Therefore, the residual mixtures of the first and second components 12and 14 are discharged from the outlet path 40 by the flow of the liquidflushing agent 46 before gelation of the hydrogel composition cansubstantially occur. Clogging of the outlet path 40 is thereby preventedor moderated.

Thus, the assembly of valves V1, V2, and V3 is automatically placed inthe first flow condition in response to localized pressure conditionswhenever P(A) is applied, and conversely, the assembly of valves V1, V2,and V3 is automatically placed in the second flow condition in responseto localized pressure conditions immediately when an interruption of theapplication of P(A) occurs.

The purging assembly 42 can be various arranged and constructed. Asshown in FIGS. 1 and 2, the source 44 of the liquid flushing agentcomprises a canister barrel 50 including a piston 52 that is biased by aspring 54 to advance within the canister barrel 50.

In this arrangement, the purging path 48 includes a conduit that leadsfrom an outlet of the canister barrel 50 into the outlet path 40 of theapplicator 30. In the illustrated embodiment, the purging path 48includes a molded fitting 56 defining a lumen on the applicator 30, anda length of flexible tubing 58 coupled at one end to the fitting 56 (bya disconnecting luer lock) and at the other end to the outlet of thecanister 50 (which can include a disconnecting luer lock as well). In analternate embodiment, the canister 50 and purging path 48 can compriseintegrally attached components of the applicator 30. In thisarrangement, the valve V1 can include a conventional one-way check valveassembly that closes when pressure conditions downstream of the valve V1exceed the pressure conditions upstream of the valve V1, to prevent abackflow of fluid through the valve V1, but that is otherwise open toallow a forward flow of fluid through the valve V1. Likewise, the valvesV2 and V3 can comprise conventional one-way check valves.

In the illustrated embodiment, a manually operated safety valve VS isprovided upstream of the one-way check valve V1, to selectively togglethe purging assembly 42 between an inactivated condition (by closing thesafety valve VS) and an activated condition (by opening the safety valveVS). When in the activated condition, the constantly applied purgingpressure P(P) provides a steady drip of liquid flushing agent 46 intothe outlet path 40 in the absence of application pressure P(A) appliedby the operator using the dual syringe assembly 18. The constant dripactively clears the outlet path 40 whenever the dual syringe assembly 18is not in use.

Alternate embodiments include the use of a pneumatic pressurizedcanister of water to allow the constant drip. This embodiment replacesthe use of a spring activated piston.

Another alternative embodiment allows the water canister to be housedaway from the applicator itself. In this arrangement, the water canistercan comprise a separate component, sized and configured, e.g., to placedon or alongside the patient, coupled by flexible tubing to theapplicator. This allows the dual syringe assembly and applicator to besmaller and lighter for ease of use.

Another alternate embodiment includes using a different flushing agentbesides water. A flushing agent that will slow gelation time can allowfor better clearing of faster gelling compositions from the outlet path.

Another alternate embodiment allows, through selective operation of asafety valve, a sudden, short purge of water through the nozzle toprovide nozzle clearing. Instead of the constant purge, this embodimentmay reduce the amount of water needed and decrease the size of theoverall system. In some embodiments, the sudden, short purge can beachieved through subsequent operation of a flush trigger or button. Insome embodiments, the sudden, short burst of flushing agent isautomatically generated when the syringe plunger stops moving forward.An actuator can sense the lack of movement, activate a pulsed release offlushing agent.

The features of the invention are set forth in the following claims.

We claim:
 1. A self-purging system for delivering a hydrogel compositionformed by mixing first and second liquid components comprising, anapplicator sized and configured to mix the first and second liquidcomponents and form the hydrogel composition, the applicator includinginlet paths that convey the first and second liquid components subjectto a selectively applied application pressure P(A) into an outlet pathfor mixing and formation of the hydrogel composition for discharge fromthe outlet path, and a purge assembly comprising a source of liquidflushing agent subject to a substantially constantly applied purgepressure P(P) that is maintained at a magnitude that is less than P(A),and a purging path coupling the source to the outlet path to conveyliquid flushing agent into the outlet path subject to the substantiallyconstantly applied purge pressure P(P), the purge assembly furtherincluding a valve assembly communicating with the purging path and theoutlet path being operable in response to localized pressure conditionsin first and second flow conditions, the first flow condition permittingthe flow and mixing of the first and second liquid components but notthe liquid flushing agent in the outlet path during the application ofP(A), for dispensing the hydrogel composition from the outlet path, thesecond flow condition permitting the flow of liquid flushing agent butnot the first and second liquid components in the outlet path subject tothe substantially constantly applied purge pressure P(P), forcontinuously flushing residual hydrogel composition from the outletpath, the valve assembly being automatically placed in the first flowcondition in response to localized pressure conditions whenever P(A) isapplied, the valve assembly being automatically placed in the secondflow condition in response to localized pressure conditions during aninterruption of the application of P(A).
 2. A system according to claim1, wherein the valve assembly includes a first valve element between thesource and the outlet path operable in response to localized pressureconditions within the purging path between a closed condition and anopened condition, in the closed condition, the first valve elementpreventing pressurized flow of the liquid flushing agent through thepurging path, in the opened condition, the first valve element allowingpressured flow of the liquid flushing agent through the purging path,the first valve element being sized and configured to assume the closedcondition when pressure conditions in the purging path downstream of thefirst valve element exceed the pressure conditions in the purging pathupstream of the first valve element.
 3. A system according to claim 2,wherein the valve assembly includes second and third valve elements inthe inlet paths of the applicator upstream of the outlet path, eachsecond and third valve element operating in response to localizedpressure conditions within the respective inlet path between a closedcondition and an opened condition, in the closed condition, each secondand third valve element preventing the flow of liquid through therespective inlet path away from the outlet path, in the openedcondition, each second and third valve element allowing the flow ofliquid through the respective inlet path toward the outlet path, eachsecond and third valve element being sized and configured to assume theclosed condition when pressure conditions upstream of the second andthird valve elements are less than the pressure conditions in therespective inlet path downstream of the second and third valve elements.4. A system according to claim 1, wherein the valve assembly includes afirst one-way valve element in the purging path downstream of thesource, and second and third one-way valve elements in the inlet pathsfor the first liquid component and second liquid component,respectively, upstream of the outlet path.
 5. A system according toclaim 1, wherein the purge assembly includes a manually operable controlelement to selectively enable and disable operation of the purgeassembly.
 6. A system according to claim 5, wherein the control elementincludes a valve in the purging path manually operable between a closedcondition disabling operation of the purge assembly and an openedcondition enabling operation of the purge assembly.
 7. A systemaccording to claim 1, wherein the source comprises a vessel, and whereinthe substantially constantly applied purge pressure P(P) comprisesoperation of a spring biased piston within the vessel.
 8. A systemaccording to claim 1, wherein the source comprises a vessel, and whereinthe substantially constantly applied purge pressure P(P) comprisespneumatic pressure within the vessel.
 9. A method for delivering ahydrogel composition comprising, forming the hydrogel composition byconveying separate first and second liquid components subject to aselectively applied application pressure P(A) into an outlet path formixing, discharging the hydrogel composition from the outlet path by theapplication of the pressure P(A), and coupling to the outlet path asource of liquid flushing agent subject to a substantially constantlyapplied purge pressure P(P) that is maintained at a magnitude that isless than P(A), establishing, in response to localized pressureconditions when P(A) is applied, a first flow condition permitting flowand mixing of the first and second liquid components in the outlet path,while simultaneously blocking the flow of the liquid flushing agent inthe outlet path, for dispensing the hydrogel composition from the outletpath, and establishing, in response to localized pressure conditionswhen the application of P(A) is interrupted, a second flow conditionpermitting the flow of the liquid flushing agent in the outlet pathsubject to the substantially constantly applied purge pressure P(P),while simultaneously blocking the flow of the first and second liquidcomponents into the outlet path, to continuously flush residual hydrogelcomposition from the outlet path during an interruption of P(A).
 10. Amethod according to claim 9, further including selectively enabling ordisabling the establishment of the second flow condition.